Railway traffic controlling apparatus



c.v E. STAPLES 4 Y 2,230,851

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 2l. 1940 Patented Feb. 4, 1941 UNITED STATES PATENT CFFCE lRAILWAY TRAFFIC CONTROLLING APPARATUS Application June 21, 1940, Serial No. 341,692

7 Claims.

My invention relates to railway trafc controlling apparatus, and it has particular reference to the organization 4of such apparatus into railway traffic controlling systems of the class 5 wherein coded trackway energy of the frequency code type is utilized to control either or both Wayside signals and train-carried cab signals.

Railway traine controlling systems of the class utilizing trackway energy of the frequency code 1U type generally employ code selecting or distinguishing units constructed :and arranged to be selectively responsive to the several diierent rates of code with which they are used. These uni-ts may be employed to control wayside or train-carried traic -controlling apparatus according as the decoding units are located in lthe trackw-ay or are carried on a train. Usually, the wayside apparatus controlled -by such units comprises multiple indication wayside signals, while the train-carried apparatus comprises either or both cab signals an-d automatic train control apparatus.

In such systems, it is often desirable to supplement the usual number lof indications controlled by the wayside or train-carried apparatus. For example, it is particularly desirable to provide :additional or supplemental indications on high-speed trains in order that such trains may be operated at all times at the maximum speeds permissible under each different trafc con-dition in the trackvsray` These supplemental indications may be used not only for the purpose of increasing the number `of indications displayed by sig- I nals throughout the protected stretch of track- Way to control the spacing of trains -along the stretch, but also may be used for the purpose of indicating the presence of fixed hazards at particular locations along the stretch, the pos-itions of switches in advance of the train, and for other similar purposes.

In veiw of the above-mentioned and other important considerations, it is an object of my present invention to provide novel and improved means which may be incorporated into existing systems of the class named to increase the number of indications controlled by such systems.

Another object of my invention is the provision of novel and improved means Wherewith -a modulation lof one of the usual code rates causes an additional or supplemental indication to be displayed on trains equipped with decoding apparatus embodying my invention but other trains equipped with the usual or standard decoding apparatus :are not aiected by such modulations and are caused to display the indication corresponding to such one code rate.

A further object of my invention is the provision of novel `and improved decoding means selectively responsive to and operated by modulations of one of the usual code rates to control a less restrictive indication than is usually controlled by the said one code rate.

An additional object of my invention is to provide novel and improved decoding apparatus for eii'ecting the above-mentioned additional less restrictive indication while at the same time main-taining all the usual precautions and safety features desirable in such systems.

The above-mentioned and other import-ant objects and characteristic features of my invention which will become readily apparent from the following description are attained in accordance with my invention by providing in .a system of the class named hav-ing decoding apparatus selectively responsive to each of the usual code rates, additional apparatus selectively responsive to a particular code rate periodically modulated at another rate differing from all of the usual code rates and higher than such rates, and utilizing such addition-a1 apparatus for controlling .a supplemental indicator or for increasing the number of controls established by the usual decoding apparatus over a multiple indication signal.

The invention further cons-ists in the `parts and in the organization and combination of such parts, which will be made more clear presently.

I shall describe two forms of .apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view illustrating a preferred form of apparatus embodying my invention. Figs. 2 and 3 represent typical forms `of trackway energy which may be used to effect selective control of `the apparatus embodying my invention and illustrated in Fig. 1. Fig. 4 i-s a diagrammatic View showing a modified arrangement of a portion of the apparatus shown in Fig. l, and also embodying my invention.

Similar reference characters have .been employed in Figs. 1 and 4 to designate corresponding par-ts in the two views.

Referring to Fig. l, the reference characters I and la designate the track rails of a stretch of railway track over which traffic normally moves in the direction indicated by an arrow, or from left to right as viewed in the drawing. The-se track rails are divided by means of the` usual insulated joints 2 into a plurality of successive adjoining track sections, of which only one section, D-E, is shown complete in the drawing.

The rails of section D-E are supplied with trackway energy from a suitable source of current, such, for example, as a source of alternating current compri-sing a generator not shown but having its opposite terminals designated by the reference characters BX and CX. This trackway energy is periodically interrupted or coded at one or another of the customary plurality of code rates by means of a coding device or transmitter CT. The device CT may take any one of many well-known forms but is illustrated as comprising a plurality of rotatable cams each designated by the reference character K with a distinguishing suffix. The cams K are driven at a constant speed of, say, fifteen revolutions per minute by a motor m which is constantly supplied with alternating current so that the coder is continuously active. vEach of the cams K is provided with a different number of teeth or projections spaced about its periphery, which teeth successively operate an associated contact member to close periodically a circuit controlling contact as the cam is rotated. For example, cam KI is shown provided with twelve teeth or projections, each of which successively engages a contact member I to close periodically a circuit controlling contact 1 8; and cams K2 and K3 are shown provided with eight and ve teeth, respectively. The projections of cam K2 engage one or another of two associated contact members 9 and I0, to close periodically contacts 9-I I and IIl-I2'when such members are engaged, and closing contact III- I3 when member I is not engaged by the projections of cam K2. The projections of cam K3 engage a contact member I4 to close periodically a circuit controlling contact Ill-I5. Cam K4, as shown, is provided with but one tooth or projection, and is provided with an associated contact member I6 which closes a normally closed circuit controlling contact II-I 8 which is opened once in each revolution of the cam when the tooth of such cam engages contact member I6. Whenever contact I6I8 is opened by the tooth of cam K4, however, a second circuit controlling contact IB-I'I is closed. The single tooth of cam K4 is designed to close contact IS-II for a selected interval preferably equal in duration to the interval that a single tooth of one of the other cams closes its associated circuit controlling contact. For the purpose of this description, I shall assume that the single tooth of cam K4 is proportioned to close its circuit controlling contact IG--I'I for an interval substantially equal in duration to the time that any one projection of cam K2 closes the associated contact Ill-IZ. In addition, I shall assume that the single tooth of cam K4 is so located on the periphery of the cam that contact IIi--II is closed during the last half of an interval that a projection on cam K2 closes contact III- I2 and the first half of the succeeding interval that contact |0-I2 is opened due to the space between such projection and the next succeeding projection on cam K2.

In accordance with certain predetermined conditions, one or another of the above-mentioned contact members operated by coder CT is conditioned to interrupt periodically or code the current that is supplied to the rails of section D-E over one or another of a plurality of circuits shortly to be traced, and which circuits, as indicated in the drawing, may be controlled by suitable apparatus responsive to traiiic conditions in advance, whereby7 the supply of trackway energy is made responsive to traffic conditions on the stretch in advance of section D-E. The details of the traffic controlled apparatus controlling the supply of trackway energy is not shown in the drawing since it forms no part o'f my present invention, but such apparatus may comprise the usual control relays governed through the medium of the usual coded track circuit apparatus to set up or establish one or another of a plurality of circuits over which energy may be supplied to the primary winding of a track transformer TT, which transformer has its secondary winding connected, in series with the usual current limiting impedance (not shown), across the track rails I and Ia adjacent exit end E of section D-E. As is readily apparent from an inspection of the drawing, one of the plurality of circuits above-mentioned includes contacts 'I- of coder CT and since such contact is operated by each of the twelve teeth of cam KI of coder CT, energy flowing in such circuit is periodically interrupted or coded at a rate of 180 interruptions per minute. A second of the plurality of circuits includes contact 9--II of coder CT, which contact is operated by each of the eight teeth of ca-m K2 and hence energy flowing in this circuit is periodically interrupted at a rate of 120 times per minute. the plurality of circuits shown includes contact I4-I5 of coder CT, which contact is operated by each of the ve teeth of cam K3 and-as a result energy flowing in this circuit is periodically interrupted '75 times per minute. A fourth circuit illustrated in Fig. 1 comprises two parallel paths a rst of which includes in series contacts Ill-I2 and IIi--II of coder CT, and the second of which includes contacts Ill- I3 and IG-IB of coder CT. Contacts I0-I2 and l0-I3 of coder CT are controlled by each of the eight teeth of cam K2 in such manner that the two contacts are alternately opened and closed at a rate of 120 times per minute; contacts I-I'I of coder CT is operated to a closed position for an interval of one-fourth second once in each revolution of cam K4 or at a rate of 15 times per minute; and contact I G--I is normally closed but is opened once in each revolution of cam K4 or at a rate of times per minute, for a corresponding interval of one-fourth second.

I have represented in Fig. 2 the manner in which energy flowing in the above-mentioned fourth circuit of the plurality is controlled by the two cams K2 and K4 of coder CT. In Fig. 2, the on periods during which energy flows is represented by the raised portions of the curve while the depressed portions of the curve represents the oif periods when no current flows. It is to be noted that due to the position of the single too-th on cam K4 with respect to the positions of the teeth of cam K2, cam K4 functions once in each revolution of the cam or once each four seconds to modulate or modify the energy supplied over contact Ill-I3 of coder CT by providing two cycles of on and off periods of double rate or 240 code. As can be seen from an inspection of Fig. 2, the modified portions of such energy are relatively short and are separated by relatively long intervals of 120 code. For comparison, I have shown in Fig. 3 unmodulated 120 code such as is supplied over the one of the plurality of circuits which includes contact Q-II of coder CT. It :should be noted that A third of A the on and "ofF periods of the code (Fig. 3) or of the unmodulated portion of the 120 code energy shown in Fig. 2 each are some one-fourth of a second in duration, while the on and off periods of the modulated portion of the 120 code each are only one-eighth of a second in duration.

In connection with a stretch Iof railway track supplied with trackway energy of the type hereinbefore described, I provide suitable decoding apparatus operated by energy received from the trackway and selectively responsive to each one of the customary code rates and to the modified or modulated code rate. I have illustrated in Fig. 1 such apparatus incorporated into a traincarried control system, shown provided for a train W represented as occupying section D-E. The train W, as shown, is provided with the usual two receiving coils 2| and 22 carried by the train in advance of its first pair of wheels and located in inductive relation with the track rails l and la, respectively. These coils are connected in series in such manner that voltages induced therein by alternating current flowing in opposite instantaneous directions in the rails -l and la are additive, and the coils are connected through the medium of the usual amplier A to a master code following relay MR. Toy accord with the usual practice, I shall assume that relay MR is constructed and arranged to operate its armature alternately first in one direction and then in the other for each impulse of current received by the coils 2li and 22 from the rails l and la.

The .reference character CB designates a trainoarried governing device here shown, for example, as a four-indication cab signal comprising a clear lamp 4l, an approach medium lamp 42, an approach lamp 43 and a slow speed lamp 44, The signal CS is selectively controlled through the medium of suitable decoding apparatus, later to be referred to, to one or another of tsfsignal control aspects in accordance with the code rate at which energy is received from the rails of the trackway.

The decoding apparatus which controls cab signal CS is indicated in the drawing as including three decoding relays Rl, R2 and R3, which relays are controlled by master relay MR in such manner that relay RI is energized and picked up whenever relay MR responds to coded energy received from the rails of the trackway; relay R2 is picked up when relay MR responds to r2() code received from the rails of the trackway; and relay R3 is picked up only when relay MR responds to code received from the trackway.

The decoding relays Rl, R2 and R3 selectively control signal CS by setting up one or another of a plurality of energizing circuits one for each lamp of the signal. The energizing circuit of lamp 4I is set up whenv and only when relay R3 is picked up; the energizing circuit of lamp 42 is established when and only when relay R3 is released and relay R2 is picked up; the energizing circuit of lamp 43 is completed when and only when relays R3 and R2 are released and relay Rl is picked up; and the circuit of lamp 44 is rendered effective to illuminate such lamp when relays Rl, R2 and R3 are all released. It iollows, therefore, that the decoding relays associated with the master relay MR selectively control signal CS in accordance with the code rate at which the trackway energy is received from the trackway.

The details yof the apparatus whereby relays RI, R2 and R3 are selectively controlled by relay MIR and in turn selectively control the cab signal CS, are not shown in the drawing since they form no part of my present invention, but such apparatus may take any suitable form such, for example, as the form illustrated and described in United States Letters Patent No. 1,986,679 granted January l, 1935, to L. V. Lewis tor Railway trafc controlling apparatus, wherein the relays RI, R2 and R3 of the patent correspond respectively to relays RI R2 and R3 of the present application, and similarly, the lamps 4l, 42, 43 and 44 of the patent correspond respectively to lamps 4|, 42, 43 and 44 of cab signal CS of the present application.

In connection with decoding apparatus of the type hereinbefore described, I provide additional o-r supplemental decoding apparatus selectively responsive to modulations of a particular one of the customary code rates and particularly eiective to provide in utmost safety a less restrictive indication than is provided by such particular one of the code rates. In Fig. 1 is represented a preferred form of such apparatus, shown as cornprising tWo relays RFS and RBS, each having slow releasing characteristics, and a slow releasing control relay RPS.

Relay RFS is provided with an energizing circuit which may be traced from terminal B of a suitable source of current, such as a battery not shown, through front contact 2c of relay R2 (selectively operated by the =120 code energy), back contact 21 of relay R3' (selectively operated by the 180 code energy), contact 2K8 of relay MR (closed in one position of the armature of relay MR), and the winding of relay RF'S to terminal C. As shown, a resistor 29; is connected across the terminals of relay RFS to aid in providing such relay with slow releasing characteristics.

Relay RBS is provided with an energizing circuit extending from terminal B through front Contact 2S of relay R2, back contact 2l' of relay R3, contact 3i! of relay MR (closed in the other position of the armature of relay MR), front contact 3l of relay RFS and the winding of relay RBS to terminal C. A resistor 32 is connected across the terminals of relay RBS during the intervals that contact 3l of relay RFS is closed. The resistors v29 and 32 are preferably designed and proportioned in suchr manner as to cause the relays RFS and RBS to be suiciently slow releasing as to maintain their respective armatures picked up during the off and on periods, respectively, of the modulations interposed in the 120 code, but insufiicient to maintain such armatures picked up during the 01T and on periods of the unmodulated 120 code. The slow release periods of relays RFS and RBS may, for example, be slightly in excess of one-eighth of a second but less than one-quarter of a second in duration.

Relay RPS is provided with an energizing circuit which may be traced from terminal B through iront contact 25 of relay back contact 2l of relay Contact 33 of relay MR, front contact 34 of relay RFS, iront contact 35 of relay RBS and the winding of relay RPS to terminal C. This energizing circuit is completed only during the intervals that relay MR responds to modulated 124) code, since the slow releasing periods of relays RFS and RBS are such that their respective armatures are held picked up to complete such circuit only when double rate or 240 code energy is supplied to relay MR, and such circuit is completed on the second successive pulse of the modulated or 240 code SO that as a result relay response to the two cycles of the 240 code which v comprise each modulation of the 120 code. 'I'hat is to say, during the first on period of the 240 or modulated 120 code, relay RFS is picked up over Contact 28 of relay MR, and during the following oi period, relay RBS is picked up over contact 30 of relay MR. The rst oif period of the modulated code is but one-eighth of a second in duration (see Fig. 2), hence relay RFS is provided with a second energizing impulse during the second on period of the 240 code prior to its armature releasing and as a result its contact 34 is held closed to complete the circuit of relay RPS, which relay is supplied with energy during the interval that contact 33 of relay MR is held closed by the second on period of the 240 code. This supply of energy is interrupted when contact 33 of relay MR is opened during the off period following the second on period of 240 code, but since this off period is but one-eighth of a second in duration, the slow releasing characteristics of relays RFS and RBS function to maintain closed the circuit of relay RPS so that l relay RPS is again supplied with energy when contact 33 of relay MR is closed in response to the first on period of the unmodulated or 120 code following the two cycles of modulated or 240 code. This on period of 120 code, however, is substantially one-fourth of a second in duration so that relay RBS is caused to release at the end of its slow release period to interrupt the circuit of relay RPS.

If, now, unmodulated 120 code is continuously supplied to relay MR, then relay RPS remains deenergized since the slow releasing periods of relays RFS and RBS are such that one or the other relay releases during the one-fourth second on and oi intervals of the 120 code and consequently the energizing circuit of relay RPS is not completed. If, however, the 130 code is periodically modulated in such manner that two cycles of 240 code replace the 120 code at regularly spaced intervals, then the circuit of relay RPS is completed during each interval that the modulated code is received and relay RPS is provided with two impulses of energizing current each time its circuit is so completed. Preferably,

relay RPS is sufciently slow releasing to bridge the intervals between the modulated code. If, as has been assumed heretofore (see Fig. 2), the modulations are repeated once each four seconds, then relay RPS may have a slow release period slightly longer than four seconds in duration.

The reference character 31 designates a traiic controlling signal controlled by the supplemental decoding apparatus embodying my invention and selectively responsive to the modulations of one of the customary code rates. As shown, lamp 31 may be a. separate and distinct lamp used as a supplemental indicator, or such lamp may, if desired, be incorporated into signal CS and convert such signal into a five-indication signaling device. An energizing circuit for lamp 31 may be traced from terminal B through front contact 26 of relay R2, back contact 21 of relay R3, front contact 36 of relay RPS, the filament of lamp 31 and front contact 38 of relay RPS to terminal C.

It is to be noted that the circuits of relays RFS, RBS, RPS and of lamp 31 are conditioned to be completed only when 120 code is received from the rails of the trackway since such circuits are all carried over a front contact 26 of relay R2 and a back contact 21 of relay R3. These relays R2 and R3, as was pointed out heretofore, are picked up only in response to 120 and 180 code energy, respectively, hence it can be seen that front contact 26 of relay R2 and back contact 21 of relay R3 will be closed only when relay MR responds to 120 code so that relay R2 is picked up and relay R3 is released.

It should be pointed out that the decoding apparatus controlling the decoding relays RI, R2 and R3 ordinarily is so designed and constructed that relays R2 and R3 will be picked up when and only when relay MR is responding to 120 and 180 code, respectively, and that relay R2 preferably is provided with slightly slow releasing characteristics sufficient, at least, to maintain the relay picked up for an interval substantially equal to a cycle of 120 code. Accordingly, it can be seen that when modulated 120 code is supplied to the trackway, relay R2 is picked up in response to the relatively long intervals that 120 code is supplied to relay MR, and relay R2 is retained picked up due to its slow releasing characteristics during the interval that modulated 120 code is substituted for the 120 code; relay RPS is picked up due to the periodic modulation of such 120 code, or in other words, in response to the regularly spaced short intervals of 240 code; but relay R3 is not affected since it picks up only on 180 code. It follows, therefore, that modulated 120 code may be used to provide a less restrictive indication than is customarily controlled by unmodulated 120 code since the modulated energy does not cause any of the usual decoding apparatus except relay R2 to respond to the modulation of the 120 code and any failure of the supplemental decoding apparatus to detect the modulated code results in the control of the indication corresponding to the unmodulated 120 code; or in other words such failure would cause the more restrictive indication corresponding to the unmodulated 120 code to be displayed. Accordingly, it can be seen that the usual safeguards and protection are provided by the supplemental decoding apparatus embodying my invention. Similarly, it can be seen that if the modulated 120 code is supplied to a train equipped with the usual or standard decoding apparatus such as is illustrated in the aforesaid Lewis Patent No, 1,986,679, such apparatus will not be affected by such modulated code and it will respond as if unmodulated code were being received. It follows that my invention provides means for providing additional indications on trains equipped with decoding apparatus embodying my invention without affecting the operation of the usual or standard decoding apparatus provided on other trains not requiring such additional indications.

In Fig. 4 I have illustrated another form of supplemental decoding apparatus embodying my invention and adapted to be incorporated into the customary four-indication signaling system for providing a supplemental indication or for increasing the number of indications controlled byl such system. In Fig. 4 a decoding transformer DT comprising a center tapped primary winding 46 and a center tapped secondary winding 41 is provided to control a decoding relay RS. The primary winding 46 of decoding transformer DT is provided with energy over a circuit extending from terminal B through front contact 26 of relay R2, back contact 21 of relay R3, contact 28 of relay MR and a portion of primary winding 46 or contact 30 of relay MR and the remainder of primary winding 46 to terminal C. The secondary winding 41 of transformer DT is` connected toy relay RS through contacts 48 and 49 vof relay MR, which contacts function to convert and only when relay MR responds to the modulations of the 120 code, hence relay RS is picked up during each of the intervals that 240 code replaces the 120 code.

Relay RS controls slow releasing relay RPS, which relay in turn controls the supplemental indication 31. Anv energizing circuit for relay RPS extends from terminal B through front contact 26 of relay R2, back contact 21 of relay R3, front contact 50 of relay RS, the winding of relay RPS and front contact 5I of relay RS to terminal C. The energizing circuit of indicator 31 is similar to that traced in Fig. 1 for the corresponding indicator 31.

It is readily apparent from' an inspection of Fig. 4 that the apparatus there illustrated functions in a manner similar to the apparatus represented in Fig. 1 to control lamp 31 to its illuminated condition when 120 code is periodically modulated by intervals of double rate or 240 code. That is to say, relay RS picks up only when relay MR responds to the modulated portions of 120 code and since relay RPS is controlled over a front contact of relay RS, slow releasing relay RPS accordingly is energized to control signal lamp 31 to its illuminated condition only when intervals of 240 code are periodically substituted for 120 code, with the slow releasing intervalof relay RPS being selected to hold the armature of such relay in its energized position during the intervals that unmodulated 120 code operates relay MR.

It should be pointed out that an additional indication less restrictive than the indication ordinarily controlled by unmodulated 120 code energyis'particularly effective to supplement the usual four-indication signaling system to indicate track hazards along the stretch or the positions of switches or turn-outs in advance, and which hazards or turn-'outs require a reduction in speed of trains operating over the stretch but do not require the speed to be reduced to that called for by the approach medium aspect. By using modulated 120 code and the supplemental decoding apparatus embodying my invention, the customary four-indication signaling system may be modified to provide a supplementalindication less restrictive than the approach medium but more restrictive than clean and at Ythe same time all the safety features inherent in the frequency code system are retained.

It is to be understood, of course, that while I have described my invention as applied to traincarried apparatus, waysidek signaling apparatus may readily be provided'with supplemental decoding apparatus similar to that hereinbefore described and selectively responsive to modulations of a particular one of the code rates, for increasing the number of indications controlled by such apparatus or for providing a supplemental indication less restrictive than the indication normally controlled by the one code rate when unmodulated.

Although I have herein shown and described only two forms of railway traflic controlling apparatus embodying my invention, it is understood that various changes and modications may be `made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. The combination with a stretch of railway track having means governed by trafc conditions in advance for supplying to the track rails trackway energy which is coded at one or another of a plurality of distinctive code rates, decoding means operated by energy received from such track rails, and railway trailc controlling apparatus selectively controlled by said decoding means in accordance with the rate at which the energy received from the track rails is coded, of means for at times modifying the supply to the track rails of a particular one of said plurality of code rates whereby the track rails are supplied with energy which is coded alternately at said one rate for a relatively long interval and then at a second rate for a relatively short interval, said second rate differing from and being higher than all rates of said plurality, supplemental decoding means controlled by energy received from the track rails and selectively responsive to energy coded only at said second code rate, and railway tranic controlling means controlled jointly by said decoding means and by said supplemental decoding means.

2. The combination in a railway traflic controlling system of the class wherein a train governing device is selectively controlled by a plurality of decoding relays one relay for each of a plurality of diiferent rates of coded energy supplied to the rails of a trackway and wherein a code following relay operated by energy received from the trackway selectively controls each of the plurality of decoding relays in such manner that each decoding relay is picked up only in response to energy of its particular code rate received from the track rails, of supplemental decoding apparatus selectively responsive to modulations of a particular onev of the code rates supplied to the track rails and including a slow acting relay provided with an energizing circuit controlled by said decoding relays and by said code following relay in such manner that said circuit is rendered effective to energize the slow acting relay when and only when said particular one code rate is modulated by periodically increasing such code rate at regularly spaced intervals, and a supplemental train governing device controlled by said slow acting relay.

3. In railway traffic controlling apparatus of the class employing a code following relay receiving energy from av trackway `and a plurality of decoding relays one for each of a plurality of diiferent rates of code supplied to the trackway and wherein the code following relay controls each of the plurality of decoding relays in such manner that each decoding relay is picked Aup when and only when the code following relay is operated byV energy received from the trackway and coded at the rate corresponding to such decoding relay, the combination with the abovementioned apparatus of supplemental decoding apparatus including a slow acting relay, an energizing circuit for said slow acting relay controlled by said decoding relays and by said code following relay and effective lto energize said slow acting relay when and only when a particular one of said plurality of code rates is periodically modulated by recurrentlydoubling the code rate i of such energy at regularly spaced intervals, and

railway` traflic controlling apparatus controlled by said decoding relays Aand by said supplemental decoding apparatus.

4. Decoding apparatus for use in conjunction with a stretch of railway track having means for supplying its track rails with coded trackway energy of the frequency code type comprising al ternate on intervals during which energy iiows and off intervals during which no energy ows andl which trackway energy lat times is coded at one or another of a plurality of distinctive code ratesiand =at other times isvcoded alternately first 'at aparticular one of said code rates for a relatively long interval and then at a second rate fora relatively short interval, said second rate dili'ering from-and being higher than all of said plurality of code rates, said decoding apparatus comprising the combination with a code following relay operatively connected with the rails of said stretch and having an armature operated alternately first to one position and then to another in response to the on and off intervals respectively of such energy received from the track rails, of a first and a second slow releasing relay, an' energizing circuit for said first relay including a contact of said code following relay closed in the said one position of its armature, an energizing circuit for said second relay including a front contact of said first relay and another contact of said code following relay closed in the other position yof its armature, said first and second relays each having a slow release period sufcient to bridge the o intervals of said second -code rate but insuflicient to bridge the off intervals of any of said plurality of code rates, a slow releasing controlrelay having a slow release period sufficient tofbridge the relatively long alternate intervals of said. one code rate intervening betweenv successive intervals of said second code rate, an energizing circuit for said control 40 relay including in series a front contact of said rst relayrand a front contact of said second relay and a contact of said code following relay closedvin said one position of its armature, and railway traffic controlling apparatus controlled 45 by said control relay.

5. Decoding apparatus for use in conjunction with a stretch ofrailway track having means for supplying its track rails with coded trackway energy of the frequency code type comprising alternate on intervals during which energy ows and off intervals during which no energy iiows and which trackway energy at times is 4coded at one orfanother of a plurality of distinctive code rates and at other times is coded alternately rst at a particular one of said code .rates for a relatively long interval and thenat a second rate for a relatively short interval, said second rate differing from and being higher than al1 of said plurality of code rates, said decoding apparatus comprising the combination with a code following relay operatively connected with the rails of said stretch and having an armature operated alternately first to one position and then to'another in response to the on and off intervals of such energy received from the track rails, and a plurality of decoding relays one for each of said plurality of code rates and each decoding `relay controlled by said code following relay in such manner that each decoding relay is picked up only in response to energy of its particular code rate received from the track rails, of a'flrst anda second relay each having a slow release period suicient to bridge the 01T inter-- contact closed in said one position of the armaf ture of said code following relay, an energizing circuit for. said second relay including in series a front contact of said one decoding relay and a front contact of .said first relay and a contact closed in the other position of the armature of said code following relay, a control relay, an energizing circuit for said control relay including in series a front contact of said one decoding relay and a front contact of said first relay'and a front contact of said second relay, and traffic controlling apparatus controlled :by said control relay.

6. Decoding apparatus for use in conjunction with a stretch of railway track having means for supplying its track rails with coded trackway energy of the frequency code type comprising alternate on intervals during which energy flows and olf intervals during which no energy flows and which trackway energy at times is coded at one or another of a plurality of distinctive code rates and at other times is coded alternately first Yat a particular one of said code rates for a relatively long interval and then at a second rate for a relatively short interval, said second rate differing from and being higher than all of said plurality of code rates, said Vdecoding apparatus comprising the combination with a code Afollowing relay'operatively connected with the'rails of said stretch and having an armature operated alternately first to one position and then to another in response to the "on and off intervals of such energy received from the track rails, of a decoding transformer supplied with energy over circuit means controlled by contacts of said code following relay, a decoding relay supplied with energy from said decoding transformer and designed and proportioned with respect to said transformer in such manner that said decoding relay is picked up when and only when energy coded at said second rate is sup-2 plied to said transformer, and railway traffic controlling apparatus controlled by said decoding relay.

7. Decoding apparatus for use in conjunction with a stretch of railway track having means for supplying its track rails with coded trackway .energy of the frequency code type comprising alternate on intervals during which energy ows and"o intervals during which no energy flows and which trackway energy at times is=A the rails of said stretch and having an armature voperated alternately first to one position and then to another in response to the "0n and off intervals of such energy received from the track rails, and a plurality of decoding relays one for .each of said plurality of code rates and each decoding relay controlled by said code following relay in such manner that each decoding relay is picked up only in response to energy of its particular code rate received from the track rails,

of-a decodingtransformer supplied with energy over circuit means controlled by said code following relay and by a front contact of the one of said decoding relays that is responsive to said particular one code rate, another relay supplied designed and proportioned with respect to said decoding transformer in such manner that said other relay is picked up When and only when energy coded at said second code rate is supplied to said transformer, and railway traiiic controlling apparatus controlled by said other relay.

CRAWFORD E. STAPLES. 

